This invention relates to a method of shielding a nuclear reactor. In more detail the invention relates to a method of shielding a liquid-metal-cooled fast-breeder reactor wherein the shield also serves as a guard vessel.
Conventionally, a massive concrete shield is provided surrounding a nuclear reactor to prevent radiation from reaching the surroundings. The cost of such a shield is an appreciable fraction of the cost of the entire facility. Fast breeder reactors currently being planned and constructed are of such large size that the shielding therefor will cost many millions of dollars. The large amount of shield concrete required also hampers installation of the various components of the reactor plant and necessitates careful control of delivery and installation dates of reactor components.
In addition, to ensure that the reactor core is always covered with sodium for emergency core cooling, fast breeder reactors as presently designed include guard vessels surrounding the several components of the primary heat transport system of the reactor plant; that is, reactor, primary pumps, and intermediate heat exchangers. The present philosophy of design of these guard vessels requires that all major components be supported from above. This fact greatly complicates the design problem raised by the necessity of ensuring that earthquakes will not rupture the containment. Accordingly, consideration of alternate approaches is desirable. It must be understood that a substantial design and testing effort would be necessary before the method of this invention could actually be employed to shield a large nuclear reactor.